1. Field of the Invention
This invention relates to the fabrication and use of a dental sonic scaler used for cleaning teeth.
2. Prior Art
Sonic scalers are commonly used in dental facilities to clean plaque, tartar and other hard deposits from the teeth of patients. The sonic scalers usually consist of a hand held drive assembly with a rapidly vibrating tip driven by compressed air. The drive assembly converts the energy from the compressed air to a high frequency movement of the tip.
The tip which is made of a rigid material, rapidly vibrates to remove deposits from the tooth surfaces. The shape of the tip is often hook shaped to assist the user in reaching hard to reach locations between the teeth.
Scalers are now recommended to be sterilized after each use. The recent spread of infectious diseases, such as HIV, has raised the level of care given to sterilizing dental equipment between patients. Because bodily fluids reach the exterior surface of the drive assembly, that surface must be sterilized.
The common approach to sterilize the exterior surface of the drive assembly has been to insert the entire scaler into an autoclave for steam sterilization. Autoclaving the entire scaler at high temperature results in rapid deterioration of the internal rubber components such as the o-rings and a mounting grommet used to mount the drive assembly and isolate the vibration from the outer housing. This deterioration diminishes the performance by reducing the strength of the vibrations. Repeated replacement of these components is expensive and raises the cost of maintaining the dental equipment. Further, replacing these components is troublesome.
Another problem with autoclaving the entire scaler is that it forces the user to maintain several drive assemblies so that the user can continue to work while some of the scalers are being sterilized.
As one solution to the problem, some users have been disassembling scalers of the general type shown in U.S. Pat. No. 4,330,282, and only sterilizing the exterior housing and the tip components that are exposed to the patient. This prevents degradation of the internal components, but it is time consuming to disassemble and then reassemble after sterilization. Also, some users are not adept at such operations. Further, an annular gap between the housing and the vibrating tip allows contaminants to enter the forward end of the housing.
U.S. Pat. No. 5,382,162 is directed to an ultrasonic dental scaler which includes a handpiece having an outer sheath that can be unthreaded from an electronic drive unit. The sheath can then be separately sterilized. While that approach is an improvement over sterilizing the entire unit, the unthreading operations to expose the internal drive coil takes some time. Also, the vibrating unit, a rather long rod attached to the vibrating tip, must be sterilized. In addition, the prevention of fluid into the drive unit relies on an o-ring positioned between the rod and a surrounding housing.
It is a primary object of this invention to provide a sonic scaler design that is able to be reliably sterilized repeatedly without affecting performance. Also, it is a goal to prevent contaminants from entering the forward end of the tool while isolating the handle from the vibrating tip of the tool. Minimizing the number of extra drive assemblies a dentist must maintain is also a desirable feature of the invention. Finally, the scaler should be as easy to maintain and use as current sonic scalers, and also be reasonably priced.